Engine/Transmission (1994 - 1998) 5th gear rattling and hard to shift

[JRS]

My transmission started making a rattling sound tonight in 5th gear while I was driving about 70 mph. I slowed down and try to shift out of 5th. After some slight coaxing I was able to get it out of 5th and into neutral. From there, shifting into 4th is not a problem. Afterwards, I was able to get it back into 5th by shifting slowly and very smoothly. The rattling noise has gone away. However, 5th gear shifting is met with some very slight grinding if I try to shift too fast. First four gears feel fine. It sounds like the 5th gear nut to me, but needed some opinions. Odd part is this is a rebuilt box with a fully splined 5th gear shaft. If it is the 5th gear, that would mean it lasted 4,000 miles LESS than my original factory transmission with the partially splined 5ht gear. Basically, there would have been no advantage in installing the modified box. Which leads me to think, could it be my clutch?

 

[ewcmr2]

5th gear or the main/lay shaft bearings at the rear of the gearbox. It's pretty easy to pull the tailhousing off the back of the transmission to see what's going on. Been there done both, now I have a G56...

 

[SMorneau]

I had 5th gear fail 3 times. The first two times were the nut backing off and both time 5th gear just disapeared. Like it wasn't even there you could shift to and from that position it was just like another neutral. The third time the synchro failed and I could not get it out of 5th. With the camper on back and a boat behind that was bad news.

I would not shift it into 5th again if I were you as it may get stuck there.

 

[JRS]

thanks for the heads up abou the synchro, did not consider that. does the transmission have to be taken completely apart to change the 5th gear synchro?



I was getting ready to order a new 2010 in a few days, so will be selling the truck in a few months. Not looking forward to having to pull the whole box, take it all apart, etc. But if that is what it takes to do it right, that's what I will do.

 

[GAmes]

Like SMorneau, there was no warning when my 5th gear nut came off. I was cruising down the highway at 70, then I wasn't. No noise, no nuthin'. Sounds like synchros to me.

 

[JRS]

Thrust washer failed, half of it wedged itself behind the fifth gear. rotating edge of broken washer tore ear off of shift fork. other half of thrust washer sitting in bottom of case. will attach photos later

 

[JRS]

attached is a photo of the damage